Welcome to our community, Gary
RoboHelp doesn't quite work that way. Normally you have all
the content static and present on either a server or inside a .CHM
file. Much like a static Web Site would work.
Assuming you are creating web based help, I suppose it would
be possible to achieve what you are looking for by creating
Framesets or Inline Frames. Then populating a frame with dynamic
content.
Perhaps if you can more fully flesh out exactly what choosing
a particular customer number would result in, we might offer some
alternatives for achieving it using RoboHelp.
Cheers... Rick